Re^2: opened file being overwritten


#!/bin/Perl
use warnings;

if (@ARGV < 4) {
    print ("you need to provide 4 arguments\n\t4th argument is file to
+ parse");
    exit;
    
}

$fh = pop(@ARGV);

openfile(@ARGV);


sub openfile {
    
    open FILE1,">$_[0]" || die "could not open $_[0]";
    open FILE2,">$_[1]" || die "could not open $_[1]";
    open FILE3,">$_[2]" || die "could not open $_[2]";
    open FILE4,"<$fh" || die "could not open $fh";
    
        while (<FILE4>) {
    
print $_;    
}
    
    

}
[download]

this makes no sense why the FILE4 file handle wont be printed i opened it for reading

Comment on Re^2: opened file being overwritten Download Code

Replies are listed 'Best First'.
Re^3: opened file being overwritten by 2teez (Vicar) on Dec 13, 2012 at 21:31 UTC
from open, `If MODE is ">", the file is opened for output, with existing files first being truncated ("clobbered") and nonexisting files newly created. If MODE is ">>", the file is opened for appending, again being created if necessary.` So, your files `$_[0] to $_[3]`, is been "clobbered", by the ">" mode, while the last one should print out. If you tell me, I'll forget. If you show me, I'll remember. if you involve me, I'll understand. --- Author unknown to me	[reply] [d/l]
Re^3: opened file being overwritten by Anonymous Monk on Dec 13, 2012 at 22:07 UTC
Another large bug in your code is that due to operator precedence, your `die`s won't work. Basically, `open FILE1,">$_[0]" \|\| die "could not open $_[0]"` is being interpreted as `open FILE1,(">$_[0]" \|\| die "could not open $_[0]")` `$ perl -MO=Deparse -e 'open INP, "<", "hello" \|\| die $!' + open INP, '<', 'hello'; -e syntax OK $ perl -MO=Deparse -e 'open(INP, "<", "hello") \|\| die $!' + die $! unless open INP, '<', 'hello'; -e syntax OK $ perl -MO=Deparse -e 'open INP, "<", "hello" or die "could not open: +$!"' die $! unless open INP, '<', 'hello'; -e syntax OK` [download] You either need to use the lower-precedence `or` operator or call the `open()` function with parentheses.	[reply] [d/l] [select]


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